Mismatched compression glass-to-metal seal

ABSTRACT

A reverse mismatched compression glass-to-metal seal is described. In this seal, the coefficient of thermal expansion of the insulating glass is lower than that of the terminal lead and, the ferrule or casing body has a similar or higher coefficient of thermal expansion than that of the terminal lead.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] The present application claims priority based on provisionalapplication Ser. No. 60/202,015, filed May 4, 2000.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention generally relates to the conversion ofchemical energy to electrical energy and, more particularly, to aglass-to-metal seal (GMTS) for hermetically sealing an electrochemicalcell. The glass-to-metal seal is considered critical because ithermetically isolates the internal environment of a component from theexternal environment to which the component is exposed. Inelectrochemical cells powering implantable medical devices, the GTMShermetically seals the internal cell chemistry from the internal deviceenvironment.

[0004] 2. Prior Art

[0005] The glass-to-metal seal of an electrochemical cell consists of aferrule sleeve secured to an opening in the cell casing, such as in thelid or in the casing body itself. The ferrule supports an insulatingglass in a surrounding relationship and the glass in turn seals aroundthe perimeter of a terminal lead. The terminal lead extends from insidethe cell to a position outside the casing, and serves as the lead forone of the cell electrodes. Typically the terminal lead is connected tothe cathode current collector. The casing including the lid serves asthe second terminal for the other electrode, typically the anode. Thisconfiguration is referred to as a case-negative design.

[0006] To construct a glass-to-metal seal, insulating glass is providedin a ring shape to fit inside the ferrule sleeve or inside an opening inthe casing body in a closely spaced relationship. The insulating glasshas a hole through its center which receives the terminal lead in aclosely spaced relationship. These components are assembled and thenheated in an furnace. This heating step causes the glass to soften andflow into intimate contact with the inside of the ferrule and with theperimeter of the terminal lead. When the assembly cools, the insulatingglass is bonded to the ferrule and the terminal lead.

[0007] Glass-to-metal seals are defined by the coefficient of thermalexpansion of the materials of construction. Conventional glass-to-metalseals fall into two main types. The first is a matched seal where thecoefficient of thermal expansions of all of the materials ofconstruction are reasonably similar. The other is referred to as acompression seal. In this type, the coefficient of thermal expansion ofthe ferrule sleeve or of the casing body is higher than that of theinsulating glass while the coefficients of thermal expansion of theterminal lead and the insulating glass are substantially the same.Compression type glass-to-metal seals are shown in U.S. Pat. No.3,225,132 to Baas et al., U.S. Pat. No. 4,053,692 to Dey, U.S. Pat. No.4,430,376 to Box and U.S. Pat. No. 4,587,144 to Kellerman et al.

SUMMARY OF THE PRESENT INVENTION

[0008] The present invention is directed to a reverse mismatchedcompression glass-to-metal seal where the coefficient of thermalexpansion of the insulating glass is less than that of the terminal leadand, the ferrule or casing body has a coefficient of thermal expansionwhich is substantially similar to or significantly greater than that ofthe terminal lead. Theoretically, seals made with a terminal lead havinga coefficient of thermal expansion greater than the insulating glassshould display stress levels that compromise hermiticity.

[0009] These and other objects of the present invention will becomeincreasingly more apparent to those of ordinary skill in the art byreference to the following description and the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010]FIG. 1 is a schematic view of an exemplary glass-to-metal sealhaving a ferrule supporting the insulating glass.

[0011]FIG. 2 is a schematic view of an exemplary glass-to-metal sealhaving the glass sealed directly to the casing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] A typical hermetic glass-to-metal seal consists of a terminallead electrically isolated from a ferrule or the casing body by aninsulating glass. The individual materials chosen for these applicationsare critical and must meet the following design criteria. First, theterminal lead must be corrosion resistant to the internal cellchemistry, be weldable and modifiable for attachment to the end usersproduct, and have sufficient electrically conductivity for theparticular cell design. Secondly, the insulating glass needs to becorrosion resistant to the internal cell chemistry, and have sufficientelectrical resistivity for the particular cell design. Lastly, theferrule or casing body must be corrosion resistant to the internal cellchemistry, have sufficient electrically conductivity for the particularcell design, and be weldable for secondary operations.

[0013] When these components are manufactured into a glass-to-metalseal, accomplished by assembling the components together followed byheating in a furnace, the resultant seal must also meet the followingdesign criteria: the assembly must be hermetic, the insulating glassmust exhibit acceptable visual characteristics, i.e., have no cracksthat affect function, and there must be sufficient electricalresistivity between the ferrule or casing body and the terminal lead forthe cell design. Also, the glass-to-metal seal must exhibit acceptablethermal resistant to secondary processing such as welding and it must bemechanically tolerant to secondary processing such as terminal leadbending.

[0014] Turning now to the drawings, FIGS. 1 and 2 show exemplaryembodiments of glass-to-metal seals of both the conventional matched andcompression types and of the mismatched type according to the presentinvention. As already discussed, it is not the specific configuration ofthe various components of the seals, but the materials of constructionwhich delineates the prior art from the present invention seals.

[0015] As shown in FIG. 1, one exemplary embodiment of a glass-to-metalseal 10 consists of a casing 12 having an opening sized to receive aferrule 14. The casing 12 can be the casing body itself or a lid securedto the open end of a container housing the electrode assembly (notshown), as is well known by those of ordinary skill in the art. Theferrule 14 is a cylindrically-shaped member hermetically secured to thecasing in the opening, such as by welding. Preferably, the upper end ofthe ferrule is flush with the outer surface of the casing 12. Theferrule extends into the interior of the casing and supports aninsulating glass 16 surrounding the perimeter of a terminal lead 18. Theterminal lead 18 is coaxial with the ferrule and one end extends intothe interior of the casing. This end is connected to one of theelectrodes, typically the current collector (not shown) of the cathodeelectrode. The other end of the terminal lead 18 extends above theferrule 14 and the outer surface of the casing 12 and provides forconnection to one of the terminals of the load which the cell isintended to power.

[0016] The other lead of the cell is provided by the casing electricallyconnected to the anode electrode. This electrode configuration isreferred to as a case-negative design. As is well known by those ofordinary skill in the art, the cell can also be provided in acase-positive configuration. In that case, the terminal lead 18 isconnected to the anode current collector and the cathode electrode iselectrically connected to the casing.

[0017] In any event, the glass must be sufficiently resistive toelectrically segregate the casing 12 from the terminal lead 18 but besealed to and between the ferrule 14 and the terminal lead. This sealingrelationship must be sufficiently hermetic so that the cell is useful inapplications such as powering implantable medical devices.

[0018]FIG. 2 shows another embodiment of an exemplary glass-to-metalseal 20 devoid of a ferrule. This assembly includes a terminal lead 22sealed directly into an opening in the casing 24 by an intermediateinsulating glass 26. Again, the casing can be the casing body itself ora lid for the casing, and the terminal lead is connected to the cathodewhile the casing serves as the anode terminal for a case-negative celldesign.

[0019] In that respect, the materials of construction for both theexemplary embodiments of glass-to-metal seals shown in FIGS. 1 and 2must meet the various criteria set forth above. However, the presentinvention improves upon the hermeticity of the prior art seals byproviding a glass-to-metal seal which is neither of a typical matched orcompression type. Instead, the insulating glass of the presentmismatched compression seal has a coefficient of thermal expansion whichis less than, and preferably significantly less than, that of theterminal lead while the ferrule or casing body has a coefficient ofthermal expansion which is substantially similar to or significantlygreater than that of the terminal lead. The resulting glass-to-metalseal is a compression seal with a terminal lead of mismatched thermalexpansion. However, the resulting seal provides all of the criticaldesign criteria for the use in an electrochemical cell of the typeintended to power an implantable medical device.

[0020] A significantly less than or greater than coefficient of thermalexpansion is one which differs from another by more than about2.0×10⁻⁶/° C. while a substantially similar coefficient of thermalexpansion is defined as one which differs from another by less thanabout ±2.0×10⁻⁶/° C.

[0021] Embodiments of a present invention mismatched compressionglass-to-metal seal have the components of a ferrule orcasing/insulating glass/terminal lead of: 304L SS/Cabal-12/446 SS, 304LSS/Cabal-12/29-4-2 SS, 304L SS/Cabal-12/titanium alloy (grades 1 to 4, 5and 9), 304L SS/TA-23/446 SS, 304L SS/TA-23/29-4-2 SS, 304LSS/TA-23/titanium alloy (grades 1 to 4, 5 and 9), and titaniumalloy/Cabal-12/titanium alloy (grades 1 to 4, 5 and 9). Cabal-12 glassis commercially available from Sandia National Laboratories. Specificembodiments have the coefficient of thermal expansion combinations shownin Tables 1 to 5. TABLE 1 Ferrule or Casing Body Insulating GlassTerminal Lead 304L SS Cabal-12 446 SS 19 × 10⁻⁶/° C. 6.5 × 10⁻⁶/° C.11.7 × 10⁻⁶/° C. (20-600° C.) (20-500° C.) (20-600° C.) 304L SS Cabal-1229-4-2 19 × 10⁻⁶/° C. 6.5 × 10⁻⁶/° C. 9.4 × 10⁻⁶/° C. (20-600° C.)(20-500° C.) (21-100° C.) 304L SS Cabal-12 Titanium Alloy 19 × 10⁻⁶/° C.6.5 × 10⁻⁶/° C. (Gr. 1-Gr. 4) (20-600° C.) (20-500° C.) 9.7 × 10⁻⁶/° C.(20-540° C.) 304L SS Cabal-12 Titanium Alloy 19 × 10⁻⁶/° C. 6.5 × 10⁻⁶/°C. (Gr. 5) (20-600° C.) (20-500° C.) 9.5 × 10⁻⁶/° C. (20-540° C.) 304LSS Cabal-12 Titanium Alloy 19 × 10⁻⁶/° C. 6.5 × 10⁻⁶/° C. (Gr. 9)(20-600° C.) (20-500° C.) 10.8 × 10⁻⁶/° C. (20-540° C.)

[0022] TABLE 2 Ferrule or Casing Body Insulating Glass Terminal Lead304L SS TA-23 446 SS 19 × 10⁻⁶/° C. 6.3 × 10⁻⁶/° C. 11.7 × 10⁻⁶/° C.(20-600° C.) (20-695° C.) (20-600° C.) 304L SS TA-23 29-4-2 19 × 10⁻⁶/°C. 6.3 × 10⁻⁶/° C. 9.4 × 10⁻⁶/° C. (20-600° C.) (20-695° C.) (21-100°C.) 304L SS TA-23 Titanium Alloy 19 × 10⁻⁶/° C. 6.3 × 10⁻⁶/° C. (Gr.1-Gr. 4) (20-600° C.) (20-695° C.) 9.7 × 10⁻⁶/° C. (20-540° C.) 304L SSTA-23 Titanium Alloy 19 × 10⁻⁶/° C. 6.3 × 10⁻⁶/° C. (Gr. 5) (20-600° C.)(20-695° C.) 9.5 × 10⁻⁶/° C. (20-540° C.) 304L SS TA-23 Titanium Alloy19 × 10⁻⁶/° C. 6.3 × 10⁻⁶/° C. (Gr. 9) (20-600° C.) (20-695° C.) 10.8 ×10⁻⁶/° C. (20-540° C.)

[0023] TABLE 3 Ferrule or Casing Body Insulating Glass Terminal LeadTitanium Alloy Cabal-12 Titanium Alloy (Gr. 1-Gr. 4) 6.5 × 10⁻⁶/° C.(Gr. 1-Gr. 4) 9.7 × 10⁻⁶/° C. (20-500° C.) 9.7 × 10⁻⁶/° C. (20-540° C.)(20-540° C.) Titanium Alloy Cabal-12 Titanium Alloy (Gr. 1-Gr. 4) 6.5 ×10⁻⁶/° C. (Gr. 5) 9.7 × 10⁻⁶/° C. (20-500° C.) 9.5 × 10⁻⁶/° C. (20-540°C.) (20-540° C.) Titanium Alloy Cabal-12 Titanium Alloy (Gr. 1-Gr. 4)6.5 × 10⁻⁶/° C. (Gr. 9) 9.7 × 10⁻⁶/° C. (20-500° C.) 10.8 × 10⁻⁶/° C.(20-540° C.) (20-540° C.)

[0024] TABLE 4 Ferrule or Casing Body Insulating Glass Terminal LeadTitanium Alloy Cabal-12 Titanium Alloy (Gr. 5) 6.5 × 10⁻⁶/° C. (Gr.1-Gr. 4) 9.5 × 10⁻⁶/° C. (20-500° C.) 9.7 × 10⁻⁶/° C. (20-540° C.)(20-540° C.) Titanium Alloy Cabal-12 Titanium Alloy (Gr. 5) 6.5 × 10⁻⁶/°C. (Gr. 5) 9.5 × 10⁻⁶/° C. (20-500° C.) 9.5 × 10⁻⁶/° C. (20-540° C.)(20-540° C.) Titanium Alloy Cabal-12 Titanium Alloy (Gr. 5) 6.5 × 10⁻⁶/°C. (Gr. 9) 9.5 × 10⁻⁶/° C. (20-500° C.) 10.8 × 10⁻⁶/° C. (20-540° C.)(20-540° C.)

[0025] TABLE 5 Ferrule or Casing Body Insulating Glass Terminal LeadTitanium Alloy Cabal-12 Titanium Alloy (Gr. 9) 6.5 × 10⁻⁶/° C. (Gr.1-Gr. 4) 10.8 × 10⁻⁶/° C. (20-500° C.) 9.7 × 10⁻⁶/° C. (20-540° C.)(20-540° C.) Titanium Alloy Cabal-12 Titanium Alloy (Gr. 9) 6.5 × 10⁻⁶/°C. (Gr. 5) 10.8 × 10⁻⁶/° C. (20-500° C.) 9.5 × 10⁻⁶/° C. (20-540° C.)(20-540° C.) Titanium Alloy Cabal-12 Titanium Alloy (Gr. 9) 6.5 × 10⁻⁶/°C. (Gr. 9) 10.8 × 10⁻⁶/° C. (20-500° C.) 10.8 × 10⁻⁶/° C. (20-540° C.)(20-540° C.)

[0026] By way of example, in an illustrative cell according to thepresent invention, the anode active material is an alkali metal selectedfrom Group IA of the Periodic Table of Elements and contacted to anickel current collector, and the cathode active material is of acarbonaceous material, fluorinated carbon, metal, metal oxide, mixedmetal oxide or a metal sulfide, and mixtures thereof. Preferably, thecathode material is mixed with a conductive diluent such as carbonblack, graphite or acetylene black or metal powders such as nickel,aluminum, titanium and stainless steel, and with a fluoro-resin powderbinder material such as powdered polytetrafluroethylene or powderedpolyvinylidene fluoride. The thusly prepared cathode active mixture iscontacted to the cathode current collector which is a thin sheet ormetal screen, for example, a titanium, stainless steel, aluminum ornickel screen.

[0027] The separator is of electrically insulative material, and theseparator material also is chemically unreactive with the anode andcathode active materials and both chemically unreactive with andinsoluble in the electrolyte. In addition, the separator material has adegree of porosity sufficient to allow flow therethrough of theelectrolyte during the electrochemical reaction of the cell.Illustrative separator materials include woven and non-woven fabrics ofpolyolefinic fibers or fluoropolymeric fibers including polyvylidinefluoride, polyethylenetetrafluoroethylene, andpolyethylenechlorotrifluoroethylene laminated or superposed with apolyolefinic or fluoropolymeric microporous film. Suitable microporousfilms include a polytetrafluoroethylene membrane commercially availableunder the designation ZITEX (Chemplast Inc.), polypropylene membranecommercially available under the designation CELGARD (Celanese PlasticCompany, Inc.) and a membrane commercially available under thedesignation DEXIGLAS (C. H. Dexter, Div., Dexter Corp.). The separatormay also be composed of non-woven glass, glass fiber materials andceramic materials.

[0028] The exemplary cell of the present invention having the mismatchedcompression glass-to-metal seal is activated with an ionicallyconductive electrolyte which serves as a medium for migration of ionsbetween the anode and the cathode electrodes during the electrochemicalreactions of the cell. By way of example, a suitable electrolyte for analkali metal active anode has an inorganic or organic, ionicallyconductive salt dissolved in a nonaqueous solvent, and more preferably,the electrolyte includes an ionizable alkali metal salt dissolved in amixture of aprotic organic solvents comprising a low viscosity solventand a high permittivity solvent. The ionically conductive salt serves asthe vehicle for migration of the anode ions to intercalate or react withthe cathode active material. Preferably the ion-forming alkali metalsalt is similar to the alkali metal comprising the anode.

[0029] A preferred material for the casing is titanium althoughstainless steel, mild steel, nickel-plated mild steel and aluminum arealso suitable. The casing header comprises a metallic lid having asufficient number of openings to accommodate the glass-to-metal seal 10,20 having the terminal lead 18, 22 connected to the cathode electrode.An additional opening is provided for electrolyte filling. The casinglid comprises elements having compatibility with the other components ofthe electrochemical cell and is resistant to corrosion. The cell isthereafter filled with the electrolyte solution described hereinaboveand hermetically sealed such as by close-welding a stainless steel plugover the fill hole, but not limited thereto. The cell of the presentinvention can also be constructed in a case-positive design.

[0030] Further, the cell of the present invention having the mismatchedcompression glass-to-metal seal 10, 20 is readily adaptable tosecondary, rechargeable electrochemical chemistries. A typical negativeelectrode for a secondary cell is fabricated by mixing about 90 to 97weight percent “hairy carbon” (U.S. Pat. No. 5,443,928 to Takeuchi etal.) or graphite with about 3 to 10 weight percent of a binder material,which is preferably a fluoro-resin powder such aspolytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF),polyethylenetetrafluoroethylene (ETFE), polyamides, polyimides, andmixtures thereof. This negative electrode admixture is provided on acurrent collector such as of a nickel, stainless steel, or copper foilor screen by casting, pressing, rolling or otherwise contacting theadmixture thereto.

[0031] In secondary cells, the positive electrode preferably comprises alithiated material that is stable in air and readily handled. Examplesof such air-stable lithiated cathode active materials include oxides,sulfides, selenides, and tellurides of such metals as vanadium,titanium, chromium, copper, molybdenum, niobium, iron, nickel, cobaltand manganese. The more preferred oxides include LiNiO₂, LiMn₂O₄,LiCoO₂, LiCo_(0.92)Sn_(0.08)O₂ and LiCo_(1-x)Ni_(x)O₂. The secondarycell chemistry is activated by the previously described electrolytes.

[0032] To charge such secondary cells, the lithium metal comprising thepositive electrode is intercalated into the carbonaceous negativeelectrode by applying an externally generated electrical potential tothe cell. The applied recharging electrical potential serves to drawlithium ions from the cathode active material, through the electrolyteand into the carbonaceous material of the negative electrode to saturatethe carbon. The resulting Li_(x)C₆ negative electrode can have an xranging between 0.1 and 1.0. The cell is then provided with anelectrical potential and is discharged in a normal manner.

[0033] It is appreciated that various modifications to the inventionconcepts described herein may be apparent to those skilled in the artwithout departing from the spirit and the scope of the present inventiondefined by the hereinafter appended claims.

What is claimed is:
 1. An electrochemical cell comprising an anode electrode and a cathode electrode housed inside a casing and activated with an electrolyte, wherein one of the anode electrode and the cathode electrode is connected to a terminal lead insulated from the casing by a glass-to-metal seal, the improvement is the glass-to-metal seal comprising: the glass-to-metal seal having an insulating glass extending between and sealed to a support portion of the casing and the terminal lead, wherein the insulating glass has a first coefficient of thermal expansion which is less than a second coefficient of thermal expansion of the terminal lead and wherein the second coefficient of thermal expansion is less than or substantially similar to a third coefficient of thermal expansion of the casing support portion.
 2. The electrochemical cell of claim 1 wherein the first coefficient of thermal expansion is significantly less than the second coefficient of thermal expansion.
 3. The electrochemical cell of claim 1 wherein the first coefficient of thermal expansion and the second coefficient of thermal expansion differ by more than about 2.0×10⁻⁶/° C.
 4. The electrochemical cell of claim 1 wherein second coefficient of thermal expansion and the third coefficient of thermal expansion differ by less than about 2.0×10⁻⁶/° C.
 5. The electrochemical cell of claim 1 wherein the second coefficient of thermal expansion and the third coefficient of thermal expansion differ by more than about 2.0×10⁻⁶/° C.
 6. The electrochemical cell of claim 1 wherein the first coefficient of thermal expansion ranges from about 6.3×10⁻⁶/° C. to about 6.5×10⁻⁶/° C., the second coefficient of thermal expansion ranges from about 9.4×10⁻⁶/° C. to about 11.7×10⁻⁶/° C. and the third coefficient of thermal expansion ranges from about 9.5×10⁻⁶/° C. to about 19×10⁻⁶/° C.
 7. The electrochemical cell of claim 1 wherein the insulating glass is selected from the group consisting of Cabal-12 and TA-23, the terminal lead is selected from the group consisting of 446 SS, 29-4-2 SS and a titanium alloy of grades 1 to 5 and 9, and the casing support portion is selected from the group consisting of 304L SS and a titanium alloy of grades 1 to 5 and
 9. 8. The electrochemical cell of claim 1 wherein the first coefficient of thermal expansion is about 6.5×10⁻⁶/° C., the second coefficient of thermal expansion is about 11.7×10⁻⁶/° C. and the third coefficient of thermal expansion is about 19×10⁻⁶/° C.
 9. The electrochemical cell of claim 1 wherein the first coefficient of thermal expansion is about 6.5×10⁻⁶/° C., the second coefficient of thermal expansion is about 9.4×10⁻⁶/° C. and the third coefficient of thermal expansion is about 19×10⁻⁶/° C.
 10. The electrochemical cell of claim 1 wherein the first coefficient of thermal expansion is about 6.5×10⁻⁶/° C., the second coefficient of thermal expansion is about 9.7×10⁻⁶/° C. and the third coefficient of thermal expansion is about 19×10⁻⁶/° C.
 11. The electrochemical cell of claim 1 wherein the first coefficient of thermal expansion is about 6.5×10⁻⁶/° C., the second coefficient of thermal expansion is about 9.5×10⁻⁶/° C. and the third coefficient of thermal expansion is about 19×10⁻⁶/° C.
 12. The electrochemical cell of claim 1 wherein the first coefficient of thermal expansion is about 6.5×10⁻⁶/° C., the second coefficient of thermal expansion is about 10.8×10⁻⁶/° C. and the third coefficient of thermal expansion is about 19×10⁻⁶/° C.
 13. The electrochemical cell of claim 1 wherein the first coefficient of thermal expansion is about 6.3×10⁻⁶/° C. the second coefficient of thermal expansion is about 11.7×10⁻⁶/° C. and the third coefficient of thermal expansion is about 19×10⁻⁶/° C.
 14. The electrochemical cell of claim 1 wherein the first coefficient of thermal expansion is about 6.3×10⁻⁶/° C., the second coefficient of thermal expansion is about 9.4×10⁻⁶/° C. and the third coefficient of thermal expansion is about 19×10⁻⁶/° C.
 15. The electrochemical cell of claim 1 wherein the first coefficient of thermal expansion is about 6.3×10⁻⁶/° C., the second coefficient of thermal expansion is about 9.7×10⁻⁶/° C. and the third coefficient of thermal expansion is about 19×10⁻⁶/° C.
 16. The electrochemical cell of claim 1 wherein the first coefficient of thermal expansion is about 6.3×10⁻⁶/° C., the second coefficient of thermal expansion is about 9.5×10⁻⁶/° C. and the third coefficient of thermal expansion is about 19×10⁻⁶/° C.
 17. The electrochemical cell of claim 1 wherein the first coefficient of thermal expansion is about 6.3×10⁻⁶/° C., the second coefficient of thermal expansion is about 10.8×10⁻⁶/° C. and the third coefficient of thermal expansion is about 19×10⁻⁶/° C.
 18. The electrochemical cell of claim 1 wherein the first coefficient of thermal expansion is about 6.5×10⁻⁶/° C., the second coefficient of thermal expansion is about 9.7×10⁻⁶/° C. and the third coefficient of thermal expansion is about 9.7×10⁻⁶/° C.
 19. The electrochemical cell of claim 1 wherein the first coefficient of thermal expansion is about 6.5×10⁻⁶/° C., the second coefficient of thermal expansion is about 9.5×10⁻⁶/° C. and the third coefficient of thermal expansion is about 9.7×10⁻⁶/° C.
 20. The electrochemical cell of claim 1 wherein the first coefficient of thermal expansion is about 6.5×10⁻⁶/° C., the second coefficient of thermal expansion is about 10.8×10⁻⁶/° C. and the third coefficient of thermal expansion is about 9.7×10⁻⁶/° C.
 21. The electrochemical cell of claim 1 wherein the first coefficient of thermal expansion is about 6.5×10⁻⁶/° C., the second coefficient of thermal expansion is about 9.7×10⁻⁶⁶/° C. and the third coefficient of thermal expansion is about 9.5×10⁻⁶/° C.
 22. The electrochemical cell of claim 1 wherein the first coefficient of thermal expansion is about 6.5×10⁻⁶/° C., the second coefficient of thermal expansion is about 9.5×10⁻⁶/° C. and the third coefficient of thermal expansion is about 9.5×10⁻⁶/° C.
 23. The electrochemical cell of claim 1 wherein the first coefficient of thermal expansion is about 6.5×10⁻⁶/° C., the second coefficient of thermal expansion is about 10.8×10⁻⁶/° C. and the third coefficient of thermal expansion is about 9.5×10⁻⁶/° C.
 24. The electrochemical cell of claim 1 wherein the first coefficient of thermal expansion is about 6.5×10⁻⁶/° C., the second coefficient of thermal expansion is about 9.7×10⁻⁶/° C. and the third coefficient of thermal expansion is about 10.8×10⁻⁶/° C.
 25. The electrochemical cell of claim 1 wherein the first coefficient of thermal expansion is about 6.5×10⁻⁶/° C., the second coefficient of thermal expansion is about 9.5×10⁻⁶/° C. and the third coefficient of thermal expansion is about 10.8×10⁻⁶/° C.
 26. The electrochemical cell of claim 1 wherein the first coefficient of thermal expansion is about 6.5×10⁻⁶/° C., the second coefficient of thermal expansion is about 10.8×10⁻⁶/° C. and the third coefficient of thermal expansion is about 10.8×10⁻⁶/° C.
 27. A glass-to-metal seal, which comprises: a) an insulating glass; b) a terminal lead; and c) a support, wherein the insulating glass extends between and seals to the terminal lead and the support surrounding the insulating glass, and wherein the insulating glass has a first coefficient of thermal expansion which is less than a second coefficient of thermal expansion of the terminal lead and wherein the second coefficient of thermal expansion is less than or substantially similar to a third coefficient of thermal expansion of the support.
 28. The glass-to-metal seal of claim 27 wherein the first coefficient of thermal expansion is significantly less than the second coefficient of thermal expansion.
 29. The glass-to-metal seal of claim 27 wherein the first coefficient of thermal expansion and the second coefficient of thermal expansion differ by more than about 2.0×10⁻⁶/° C.
 30. The glass-to-metal seal of claim 27 wherein second coefficient of thermal expansion and the third coefficient of thermal expansion differ by less than about 2.0×10⁻⁶/° C.
 31. The glass-to-metal seal of claim 27 wherein the second coefficient of thermal expansion and the third coefficient of thermal expansion differ by more than about 2.0×10⁻⁶/° C.
 32. A method for providing an electrochemical cell comprising the steps of: a) providing an anode electrode and a cathode electrode in electrical association with each other housed inside a casing and activated with an electrolyte; b) connecting one of the anode electrode and the cathode electrode to a terminal lead; c) connecting the other of the anode electrode and the cathode electrode to the casing; d) electrically segregating the terminal lead from the casing by the provision of an insulating glass extending between and sealing to the casing and the terminal lead, wherein the insulating glass has a first coefficient of thermal expansion which is less than a second coefficient of thermal expansion of the terminal lead and wherein the second coefficient of thermal expansion is less than or substantially similar to a third coefficient of thermal expansion of the casing.
 33. The method of claim 32 including providing the first coefficient of thermal expansion being significantly less than the second coefficient of thermal expansion.
 34. The method of claim 32 including providing the first coefficient of thermal expansion and the second coefficient of thermal expansion differing by more than about 2.0×10⁻⁶/° C.
 35. The method of claim 32 including providing the second coefficient of thermal expansion and the third coefficient of thermal expansion differing by less than about 2.0×10⁻⁶/° C.
 36. The method of claim 32 including providing the second coefficient of thermal expansion and the third coefficient of thermal expansion differing by more than about 2.0×10⁻⁶/° C. 